New Account wizard; Account Type Promotions not being reset correctly

In the New Account wizard the Account Type Promotion was not being reset correctly the first time the Account Type page is shown.

If you go back a page and then forward, or change Account Type it works correctly.

For example, to recreate:

1. Create an Account Type with Promotions and a Basis of "Using a Promotion is Optional".

2. Make sure the Account Type is the default for the Product Type selected in the New Account wizard.

3. Go through the New Account wizard. On the Account Type page the Promotion textbox is "Read Only".